(1) Field of the Invention
The present invention relates to marine towing apparatus and more particularly to towed sonar array cables.
(2) Description of the Prior Art
It is known in the art to provide a winch and stowage reel assembly for deploying and retrieving a towed sonar array cable from a submarine. The winch assembly includes a driven capstan and an idling drum. In operation, the capstan rotates to bring a towed array cable onto the capstan and thence onto the drum and back to the capstan, usually for a plurality of turns, and thence onto the stowage reel. To pay out the towed array cable, which typically would have an array fixed to a free end thereof, the array being of substantially the same configuration as the cable, the capstan draws cable from the stowage reel and, after a plurality of turns around the idling drum, urges the cable through a bellmouth and out of the submarine to facilitate towing of the array well aft of the submarine's propulsion propellers. Such an arrangement is shown, for example, in U.S. Pat. No. 5,263,432 to Wood, particularly with reference to FIGS. 1 and 2 therein.
Various arrangements have been suggested by the prior art for improving the deployment of cables from bellmouths or marine vessels.
U.S. Pat. No. 4,064,358 to Smith et al. discloses a termination between a submarine coaxial cable and a submerged repeater housing. It employs an anchor assembly for transferring the load in the cable core to the repeater housing, and a protective boot assembly for surrounding and supporting the cable where it extends away form the anchor assembly. The boot assembly is rigidly connectable to the housing. Movement of the cable within the boot tube is permitted to a greater extent near the free end of the boot assembly than near the housing, by means of a flexible tube and bellmouth assembly; in order to account for the stresses associated with the cable handling and recovery.
U.S. Pat. No. 4,313,392 to Guenther et al. discloses a system for deploying and retrieving a seismic source assembly form a marine seismic vessel. The system comprises a guide track that is secured to the underside of an upper deck of the vessel. The chain, which absorbs most of the strain due to towing, passes through the track and is safely confined therein during the deployment and retrieval of the source assembly. A connector is attached to the chain at each point where a seismic source and a buoy line is to be attached. As the chain is unreeled and as each connector approaches the track, a source and a buoy line is attached to that respective connector. The track is constructed so a connector on the chain with both a source and a buoy line attached can pass therethrough. This procedure is continued until the seismic source assembly is deployed.
U.S. Pat. No. 4,317,185 to Thigpen et al. discloses a towing link consisting of spaced-apart head and tailpieces. The headpiece includes a towing eye and a pair of lugs for receiving the stress members of a streamer and a lead-in cable. The tailpiece defines a pair of bores through which the stress member and electrical conductors of the two cables are inserted and sealed. A pair of mating connector plugs is provided to interconnect corresponding conductors of the two cables.
U.S. Pat. No. 4,877,355 to VanPelt discloses a cable embedding device comprising a framework for supporting and hydraulically raising and lowering a rock saw and a cable carrying bellmouth relative to two spaced-apart sled-type runners. Each sled carries part of a jet spray system and an educator system in which the spray system creates a slurry and in which the educator system carries and discharges the slurry to the back of the device. A hinge and a hinge-roller assembly connect the framework to the device for relative movement there-between. The bellmouth is shaped to curve around the rock saw, and its pedestal foot supports the bellmouth in the cable embedding and trenching operations.
One area in which the prior art has not suggested an improvement is in preventing excessive bending of the towed array during on or off-loading from or to a barge or pier.
Conventionally, as the towed array is on or off loaded, the minimum bend radius of the towed array is occasionally violated. Even though the bellmouth at the exit point on the submarine is designed to incorporate the minimum bend radius as one of its features, it was designed to handle situations which would be encountered during typical deployment and retrieval situations at sea, not during on and off loading of the array from or to a barge or pier. In the on or off-loading scenario, the angle of the array exiting the bellmouth towards the barge is often steep enough to bend around the lip of the bellmouth that has a radius much less than the minimum bend radius.
An object, therefore, of the bellmouth exit angle adapter of the present invention is to prevent the minimum bend radius of the towed array from being violated, as the array is on or off loaded between a submarine and a barge or pier.